This invention relates to a dual-inlet gear pump wherein a drive gear is configured to receive a higher flow volume than its associated driven gear. The invention has particular application in scavenging elements that pump an air/oil mixture from an oil sump in a jet engine, or from airframe or engine mounted gearboxes.
Jet engines, such as utilized in aircraft, include a lubrication system having an oil pump for moving lubricant from an oil tank to several components associated with the jet engine. In particular, oil is delivered to gear sets utilized to take power from the jet engine and drive various accessory functions. In addition, oil is delivered to bearings for the rotating components of the jet engines, which may include gearboxes.
Typically a scavenging pump is included to return the oil back to the tank from these several components. The scavenged oil is typically mixed with air when moved by the scavenging pump away from the component.
Gear pumps are one pumping mechanism utilized as the scavenging pumps. A dual-inlet gear pump as has been utilized in this application, has included separate inlets for delivering the air/oil mixture to two rotating gears, with a common discharge. The dual-inlet gear pump typically includes a gear rotated by a gearbox-driven input drive shaft, such as from the jet engine power plant. This first gear is known as the drive gear since it engages and drives a second, or driven gear. This known scavenging pump was utilized in an application where each gear received the same supply of fluid volume.
The jet engine environment is one where space is at a premium. Thus, it would be desirable to have the scavenging pump be as small as possible, and to operate as efficiently as possible such that its size may be reduced.
Dual-inlet gear pumps are known wherein separate inlets deliver fluid to the drive and driven gears. However, these prior art gear pumps are not associated with the scavenging pump on a jet engine, nor have they been utilized as efficiently as may be desired.